Door locking means and associated control circuit for self-cleaning oven



Sept. 30, 1969 5, H, TORREY ETAL 3,469,568

DOOR LOCKING MEANS AND ASSOCIATED CONTROL CIRCUIT FOR SELF-CLEANING OVENFiled May 31, 1968 3 Sheets-Sheet 1 r l l l l? /1 'alti (gli T. Nl

35 [Sigo IN vENToRs ,Saunen H. ToRREY DONALD J, DUBUOUE NORMAN' R. SLoANSept. 30, 1969 s, H TQRREY ET Al. 3,469,568

DOOR LOCKING MEANS AND ASSOCIATED CONTROL CIRCUIT FOR SELF-CLEANING OVENFiled May 3l, 1968 3 Sheets-Sheet 2 Invanrons SUMMER H. ToRReY DouALo J.Duuaue NORMAN R. SLoAN Roesn'r L, MoRRls Sept. 30, 1969 s, TORREY ET AL3,469,568

DOOR LOCKING MEANS AND ASSOCIATED CONTROL CIRCUIT FOR SELF-CLEANING OVENFiled May 3l, 1968 3 Sheets-Sheet .j

FIGS

e I( 'III` FIG] INVENroRs SUMNER H. ToRREY DONALD J. DueuQuE NORMAN R.SLoAN ROBERT L. MORRIS United States Patent 3,469,568 DOOR LOCKING MEANSAND ASSOCIATED CON- TROL CIRCUIT FOR SELF-CLEANING OVEN Sumner H. Torreyand Donald J. Dubuque, Kankakee, Norman R. Sloan, St. Anne, and RobertL. Morris, Kankakee, Ill., assiguors to Geo. D. Roper Corporation,Kankakee, Ill., a corporation of Delaware Filed May 31, 1968, Ser. No.733,422 Int. Cl. F24c 3/00, 15/02; A211) 1/00 U.S. Cl. 126-39 10 ClaimsABSTRACT OF THE DISCLOSURE A self-cleaning range having an oven cavityand a broiler cavity with a mechanical lock for locking both of themsimultaneously during the cleaning cycle and with a control circuit soarranged that both doors must be closed and locked for a cleaning cycleto be initiated. Electrical interlock switches are associated with thedoors and enablingly connected to the thermostat when the later isturned to the upper end of its range.

It is an object of the present invention to provide a novel mechanicallocking arrangement for both the oven door and the broiler door during aself-cleaning cycle and which has provision for insuring that both doorsare closed and locked before the self-cleaning cycle may be initiated.It is a related object to provide a mechanical lock for an oven doorwith a mechanical interlock extending to the broiler door, and with thedoors being provided in addition with electrical interlocks foreffectively disabling the source of heat unless and until both doors areclosed and locked. In this connection it is a more specic object toprovide a door interlocking and latching arrangement for adjacent ovenand broiler cavities which are heated during normal usage andself-cleaned by the same broiler burner.

In general it is an object of the invention to provide both electricaland mechanical interlocks for associated oven and broiler doors with anassociated selector for selecting between the various modes of operationwhich combines a high degree of safety with inherent mechanical andelectrical simplicity.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIGURE 1 is a side sectional view of a range employing the presentinvention and taken along the line 1--1 in FIG. 2;

FIG. 2 is a front sectional view taken along the line 2 2 in FIG. l;

FIG. 3 is a perspective view of the mechanical locking and interlockingarrangement employed in the present invention;

FIG. 4 is a plan view of the lock body showing the lock member inlatched condition;

FIGS. 5, 6 and 7 show a circuit diagram comprising part of the presentinvention under conditions of baking, self-cleaning, and cooling,respectively, with the active portion of the circuit indicated by thebold lines; and

FIG. 8 is a diagram showing a typical control used in the above circuit.

While the invention has been described in connection with a lpreferredembodiment there is no intention to be limited to the embodiment shownbut it is intended, on the contrary, to cover the various alternative orequivalent constructions included Within the spirit and scope of theappended claims.

Turning now to the drawings there is disclosed in FIG- URES 1 and 2 afree-standing range 10 having a frame 3,469,568 Patented Sept. 30, 1969ICC 11 defining an oven cavity 12 and a broiler cavity 13. The latterare enclosed by doors 14, 15. For heating the oven cavity, and forpurposes of broiling in the lower cavity, a gas burner 20 is providedhaving an inlet manifold 21 which is connected via an electric valve, aswill appear, tothe usual domestic gas line.

As shown in FIG. 2, the oven is of the muffled type in which the heatedair and products of combustion do not enter the oven cavity but are,instead, directed through passageways 22-24 at the sides, top and back,discharging into a flue 25 which has a vent 26 above the level of thecooking top. The oven cavity has a catalytic smoke eliminator 30 with aninlet opening 31 and an outlet 32 which discharges into the same fluestructure 25 adjacent a barrier 33 to prevent products of combustion andassociated air from entering the oven cavity.

Arranged below the broiler burner 20 is a drip pan 35 having a rack 36,the drip pan 35 being supported in a sliding drawer 37. The broiler door15 and the drawer 37 are connected together along a hinge 38 so thatwhen the door is pulled outwardly it tips forward while pulling thedrawer 37 into full view. The door 14 which encloses the oven cavity ispivoted to the frame along a hinge axis 39. To understanding more fullythe details of the range construction, reference is made to copendingapplication Serial 733,433, iiled May 31, 1968.

A control circuit is provided for modulating the admission of gas to theburner under normal baking conditions as shown in FIG. 5, the activeportion of the circuit during baking being indicated by the bold lines.It will be helpful to have this control -circuit in mind in order tounderstand the mechanical and electrical interlocking devices which areto be described and which distinguish the present invention. Twomanually settable controls are preferably provided, an oven control anda selector switch. The oven control, indicated at 40, includes athermostat T having a contact 41. The thermostat T corresponds to theusual oven control thermostat except that, in addition to having a lowerrange covering the usual cooking temperatures, it is settable to a highrange during the self-cleaning cycle. A normally open contact 42 closeswhen the control is in its low range and a normally open contact 43closes when the control is set to its high range. An auxiliarythermostat AT, having a normally closed contact 44, is used to preventopening of the oven under high temperature conditions as will appear.

For selecting the mode of oven operation a selector switch 50 isprovided having normally open contacts 51, 52, 53. The switch isprovided with a 4-position selector knob which provides a time bake modewith all of the switches open, a bake mode with switch 51 closed, aclean mode with switch 52 closed and an unlock or cooling mode withswitch 53 closed. For timing the baking and cleaning operations, a timeclock 60 is used having a motor winding 61 and having a normally opencontact 62 which supplies a timed bus 63. An electric gas valve 65controlled by the contacts 41 of the thermostat, and in series with theusual ame switch 66, permits passage of gas to the burner when the valveis energized.

Under non-timed baking conditions shown in FIG. 5 a circuit isestablished through contacts 51 and 42 thence through contacts 41 on thethermostat T to turn on the gas valve 65, the gas flowing to the burnerbeing lit by a suitable pilot P, and with the valve being thereaftercycled automatically by the thermostat to maintain the set temperature.

In accordance with the present invention a mechanical lockingarrangement is provided for both the oven and broiler doors withelectrical interlock switches which are effective, when both of thedoors are closed and locked and when the oven control is set in its highrange, to complete a circuit from the thermostatto the gas control valvefor heating of the oven and broiler cavities to a selfcleaningtemperature. More specifically, a mechanical lock is provided for theoven door having an interlock for engaging the broiler door withelectrical interlock switches for initiating the flow of gas and with alatch for maintaining both doors closed and locked until such time thatthe temperature is again reduced to a safe level. Thus, referring toFIG. 3, the oven door 14 is provided with a lock 70 in the form of arotary striker 71 mounted on a shaft 72 and manually operated by ahandle 73. For receiving the striker there is mounted in the frame ofthe oven a lock body 75 having a receiving slot 76 which is positionedto receive the striker when the door is closed. For simultaneous lockingof the broiler door 15, a mechanical interlock is provided in the formof a rod 80 having its upper end 81 cranked with respect to the striker71 and having its lower end 82 -movable between the retracted positionshown in the drawing and a projecting position in which the lower endextends into an opening 83 in the upper edge of the broiler door andinto obstructing position with respect to a striker plate 84 mounted inthe door. Telescoped over the end of the rod is a return spring 85.

For the purpose of maintaining the striker captive within the lock body,a lock member, or lever, 90 is provided centrally pivoted at 91 andhaving a striker-receiving notch 92 at its forward end. The lock memberis held in the receptive position shown by means of a return spring 93.It will be apparent that when the striker is rotated into the slot 76and engaging the notch 92, the lock member will rotate counterclockwiseinto a latched position. For latching the lock member a latching rod 94is provided having a tip 96 which rides against a land 96 until reachinga point of drop-off 97. When the point of drop-off is reached, thelatching rod moves forwardly under the urging of a spring 98 forpositive holding of the member 90 in its locking position shown in FIG.4.

For insuring that both doors are closed and locked before gas isadmitted to the burner 20 to begin the selfcleaning cycle, a singlepole, double-throw switch 100 is provided having normally closedcontacts 101 and normally open contacts 102, which switch is in the pathof movement of the lock member 90 and operated incident to moving themember into its fully latched position. In addition a normally openswitch 103 having contacts 104 is mounted so as to be responsive tocomplete closure of the broiler door. The switch is preferably mountedin the door jam with a forwardly extending actuator 105 facing thebackside of the door.

To initiate a self-cleaning cycle (see FIG. 6), the oven control 40 isset at the high cleaning range. This, as stated, closes contacts 43 inthe oven control. Moving the selector switch 50 to its third or cleanposition closes contacts 52. Rotating the door handle 73 to the cleanposition with the broiler door closed, not only locks, and latches, bothdoors but causes contacts 102, 104 of the interlock switches to beclosed which completes an electrical circuit from the clock contacts 62through the thermostat contacts 41 to the electric valve 65. As a finalstep, the time clock 60 is set to the desired cleaning interval closingthe contacts 62 and energizing the bus 63 to open the electric valve tobegin the cleaning cycle. A circuit is simultaneously completed to theheater 106 in the smoke eliminating, or catalytic, unit 30. With thebroiler burner on, the temperature within the oven and broiler cavitiesquickly rises to the self-cleaning level which may, for example, be 750to 900 F. where cycling will take place under the control of thethermostatically operated contacts 41. When the clock has timed out theinterval, contacts 62 open thereby de-energizing the electric valve 65which turns olf the gas permitting the oven and broiler cavities tocool.

In carrying out the invention an auxiliary thermostat is provided whichcloses when the temperature is reduced to a safe level and which, actingthrough unlock contacts in the selector switch, energizes a latchrelease solenoid to release the latching rod 94, thereby to permit theoven lock to be manually rotated to its unlocking position. To establishthis unlocking mode, the selector switch is moved to its fourth orunlock position closing contacts 53 which are connected to a solenoid110, the armature of which is pinned to the rear end of the rod 94. Whena safe oven temperature is reached, which may be approximately 550 F.,closure of contacts 44 on the thermostat AT, completing the circuitshown in FIG. 7, energizes the solenoid 110 so that the latching rod ismoved out of its obstructing position. Cleaning completed, the oven andbroiler may thereaftre be used in the regular way.

For indicating that the oven and broiler are at an elevated temperature,and that the doors :are latched in closed position, a lock indicator isprovided which is preferably in the form of a gaseous discharge lampenergized through a high value series resistor 116 and with the lampbeing connected in parallel with the contacts 44. Thus, as long as thesecontacts are open, indicating that the temperature is at a high level,the lamp is turned on, but when the contacts close the lamp is shortedout and thus extinguished, indicating that the selector switch can bemoved to the unlock position.

The combination of mechanical and electrical interlocking describedabove produces a safety system which has a high degree of reliabilityand which is practically impossible to defeat. The gas cannot be turnedon for a self-cleaning cycle unless all of the conditions for safetyhave been fulfilled, i.e., unless both doors are fully closed and unlessthe rotary striker is fully bottomed in the receiving slot in the frame.It is only then that the electrical interlock switches are actuated tocomplete the circuit between the oven control thermostat and theelectric gas valve. Moreover the controls are eminently simple so thatno question is raised in the mind of the user. To establish the cleaningcycle the oven control is rotated to the high end of its range,preferably designated by the word clean, and the selector switch issimilarly moved Ato its clean position. Setting the cleaning interval onthe time clock turns the burner on. It is only after the indicator lampgoes out, indicating that the temperature has been reduced to a safelevel, that moving the selector switch to the unlock mode is capable ofenergizing the latch releasing solenoid. Such foolproof operation has-been achieved at low cost using a mechanical lock having a minimumnumber of parts and using readily obtainable switch elements.

In the following claims the term striker will be understood to mean anybolt-like locking element. The term latch is intended to include anymeans for insuring that the door lock continues to be engaged while theoven and broiler are at elevated temperature. The term rod is intendedto cover a force transmitting member. Also, the term enabling shall beunderstood to mean conditioning for operation, the opposite of disablingthe term electric valve has to do with an electrically operated gassupply valve either electro-magnetic or the electrically heated bi-metaltype while the term slot is intended to denote any recess in which thestriker is received.

We claim:

1. In a self-cleaning gas range, the combination comprising a framehaving an oven cavity and a broiler cavity arranged below it each havinga closeable door, means including a broiler burner for heating thecavities, a mechanical lock including a manually operated striker in theoven door cooperating with a slot in the frame, a mechanical interlockincluding a rod in the oven door coupled to the striker for movementtherewith and having means at its lower end for lockingly obstructingthe broiler door when the striker is moved to its locking position,means including an electric gas valve for passing gas to the burner,oven controller means including a thermostat for controlling theelectric valve, Contact means for completing a circuit from thethermostat to the electric valve during the time that the ovencontroller means is set in its normal baking range, means includinginterlock switches associated with the mechanical lock and broiler doorrespectively and actuated when the doors are closed and locked forcompleting the circuit from the thermostat to the electric valve whenthe thermostat means is set at the upper end of its range to achieve andmaintain a self-cleaning temperature, means for turning olf the gasafter a predetermined length of time', and means for latching the doorsclosed until the temperature drops below the self-cleaning level.

2. In a self-cleaning gas range, the combination comprising a framehaving an oven cavity and a broiler cavity arranged below it, eachhaving a closeable door, a broiler burner for heating the cavities, anoven controller including thermostat means manually settable formaintaining a temperature in a baking range and a high selfcleaningtemperature, said oven door having a mechanical lock and said broilerdoor having an interlock coupled to the lock for maintaining the doorslocked during a self-cleaning cycle, means including electricalinterlock switches respectively associating with the doors and operatedincident to closing and locking both of the doors for enabling controlof the burner by the thermostat means when the controller is set for theself-cleaning temperature, and means for latching the mechanical lock inclosed position during the time that the temperature is above the bakingrange.

3. In a self-cleaning gas range, the combination comprising a framehaving an oven cavity and a broiler cavity arranged below it each havinga closeable door, a broiler burner for heating the cavities, amechanical lock including a manually operated rotatable striker in theoven door cooperating with a slot in the frame, a reciprocable push rodin the oven door having a cranked connection with the rotatable strikerat its upper end and having means at its lower end for obstructing thebroiler door when the striker is moved to locking position, meansincluding a controller having a thermostat and settable to a high levelfor operating the burner to achieve a seltcleaning temperature, meansincluding electrical interlock switches associated with the respectivedoors and operated when theI doors are closed and locked for enablingoperation of said thermostat, means for turning olf the gas after theself-cleaning temperature has been maintained for a `predeterminedlength of time, and means for latching the striker in locking positionduring the time that the temperature in the oven cavity is above apredetermined level.

4. In a self-cleaning gas range, the combination cornprising a framehaving an oven cavity and a broiler cavity arranged below it, eachhaving a closeable door, a broiler burner for heating the cavities, saidoven door having a mechanical lock including a manually operated rotarystriker in the door cooperating with a slot in the frame, a movablelocking member adjacent the slot for receiving the tip of the strikerand for holding it captive in the slot, a mechanical interlock includinga rod in the oven door having a cranked connection with the striker atits upper end and having means at its lower end for obstructing thebroiler door when the striker is moved to locking position, a latch forlatching the locking member, controller means including a thermostat andelectric valve associated with the burner for causing the latter to deLvelop a self-cleaning temperature in the cavities, electrical interlockswitch means operated when the doors are closed and locked for enablingthe thermostat to maintain a high self-cleaning temperature, means forturning ot the burner after the self-cleaning temperature has existedfor a predetermined length of time, and means operated incident to adrop in temperature to below the self-cleaning level for releasing thelatch thereby to permit manual opening of the door.

5. In a self-cleaning gas range, theI combination comprising a framehaving an oven cavity and a broiler cavity arranged below it each havinga closeable door, a

broiler burner for heating the cavities, a mechanical lock forsimultaneous locking of both of the doors and manually throwable fromopen to locked position, an oven controller including a thermostat andsolenoid valve for supplying gas to the burner, said controller beingsettable to a baking range and a high self-cleaning temperature, a firstswitch contact on the controller for establishing a circuit between thethermostat and electric valve when the thermostat is set within itsbaking range, a second switch contact on the controller arranged forclosure when the controller is set at the self-cleaning temperature7electrical interlock switch means associated with said doors andoperated when the doors are closed and locked, said electrical interlockswitch means being connected in series with the second switch contact toprevent turning on of the burner and achieving of a self-cleaningtemperature until the doors are closed and locked, means for turning olftheI burner after passage of a predetermined time at the self-cleaningtemperature, and means including a latch for maintaining the lock inlocked condition as long as the temperature is above a predeterminedlevel and for releasing the latch when the temperature is reduced belowsuch level.

6. In a self-cleaning gas range, the combination comprising a framehaving an oven cavity and a broiler cavity arranged below it each havinga closeable door, la broiler burner for heating the cavities, meansincluding a mechanical interlock between the doors for locking both ofthe doors simultaneously, means including an electric gas valve forpassing gas to the burner, an oven controller including a thermostatsettable to a high and low range, a selector switch settable betweenbake, clean, and door unlock modes and having rst, second, and thirdcontacts respectively closed in such modes, a bake circuit including thefirst contact for operatively connecting the thermostat to the electricvalve when the thermostat is in its low range, electrical interlockswitch means associated with said doors and arranged for actuation whenthe doors are closed and locked, a clean circuit including the secondcontact for connecting the thermostat and the interlock switch means inoperative series connection with the electric valve when the thermostatis in its high range to establish a high self-cleaning temperature,means including a latch for holding the locking means in lockedcondition and having an associated unlocking solenoid for releasing thelatch, means for turning off the ilow of gas after a predeterminedlength of time at self-cleaning temperature, an auxiliary thermostatarranged to close when the temperature falls below the self-cleaningtemperature, and a door unlock circuit including the third contact forcoupling together the auxiliary thermostat and the unlocking solenoidfor unlatching the lock when the temperature is safely below theself-cleaning temperature.

7. In a self-cleaning gas range, the combination comprising a framehaving an oven cavity and an adjacent broiler cavity each having acloseable door, burner means for heating the cavities, -a mechanicallock including a manually operated striker in one of the doorscooperating with a recess in the frame, a mechanical interlock coupledto the striker and extendable into obstructing relation with the otherdoor for holding the other door closed as long as the said one door isclosed Iand locked, means including a gas valve for passing gas to theburner means, oven controller means including thermostat meansselectively settable to maintain a baking temperature and a highself-cleaning temperature, means including an interlock switch actuatedwhen both of the doors are closed and locked for completing a circuitfrom the thermostat means to the electric valve to turn on the gas whenthe thermostat means is set to the high self-cleaning temperature, meansfor turning ofr" the ow of gas after the high temperature has existedfor a predetermined length of time, and means for maintaining themechanical lock in locked condition until the temperature falls to apredetermined safe level.

8. In a self-cleaning range, the combination comprising a frame definingan oven cavity having a closeable door, a burner for heating the cavity,said oven door having a mechanical lock including a manually operatedrotary striker in the door cooperating with a slot in the frame, apivoted locking member adjacent the slot having a notch for receivingthe tip of the striker and movable therewith into a locking position inwhich the striker is captive in the slot, a latch for latching thelocking member in locking position, controller means including athermostat arranged to control the burner for causing the latter todevelop a self-cleaning temperature in the cavity, an electricalinerlock switch in the path of movement of the locking member and closedas the locking member moves into its locking position for coupling thethermostat to the burner, means for turning off the burner after theselfcleaning temperature has existed for a predetermined length of time,and means operated incident to a drop in temperature to below theself-cleaning level for releasing the latch thereby to permit manualopening of the door.

9. ln a self-cleaning oven assembly, the combination comprising a framedefining an oven cavity having a closeable door, a burner for heatingthe cavity, a rnechanical lock for locking the door and manuallythrowable from open to locked position, means including an ovencontroller having a thermostat controllably coupled to the burner forcontrolling the heat output thereof, said controller being settable to abaking range and a high selfcleaning temperature, normally open andnormally closed switch contacts actuated incident to closing and lockingthe door, a first switch contact on the controller closed when thethermostat is set within its baking range, a second switch contact onthe controller closed when the controller is set at the self-cleaningtemperature, a baking circuit including the first switch contact on thecontroller and said normally closed contact for coupling the thermostatto the burner to establish a baking ternperature, and a self-cleaningcircuit including the second switch contact on the controller and saidnormally open contact for coupling the thermostat to the burner therebyto prevent turning on of the burner and achieving of a self-cleaningtemperature until the door is closed and locked, means for turning offthe burner after passage f a predetermined time at the selfcleaningtemperature, and means including a latch for maintaining the lock inlocked condition as long as the temperature is above a predeterminedlevel and for releasing the latch when the temperature is reduced belowsuch level.

1). In a self-cleaning oven assembly, the combination comprising a framedefining an oven cavity having a closeable door, a burner for heatingthe cavity, a mechanical lock for locking the door and throwablemanually from open to locked position, means including an ovencontroller having a thermostat controllably coupled to the burner forcontrolling the heat output thereof and settable to a high and lowrange, a selector switch settable between bake, clean, and door unlockmodes and having first, second, and third contacts respectively closedin such modes, a bake circuit including the rst contact for operativelycoupling the thermostat to the burner when the thermostat is in its lowrange, an electrical interlock switch associated with the lock foractuation when the door is closed and locked, a clean circuit includingthe second contact and the interlock switch for coupling the thermostatto the burner when the thermostat is in its high range to establish ahigh self-cleaning temperature, means including a latch for holding thelock in locked condition and having an associated unlacthing solenoidfor releasing the latch7 means for turning off the burner after apredetermined length of time at selfcleaning temperature, an auxiliarythermostat arranged to close when the temperature is safely below theself-cleaning temperature, and a door unlock circuit including the thirdcontact for connecting the auxiliary thermostat and the unlockingsolenoid for unlatching the lock when the temperature drops to below thesafe value.

References Cited UNITED STATES PATENTS 3,050,048 8/1962 Scott 126--2733,364,912 1/1968 Dills etal.

3,406,677 10/1968 Anderson 126--273 X 3,416,515 12/1968 Mettler 126-273CHARLES I. MYI-IRE, Primary Examiner U.S. C1.X.R. 126-197, 273

